473733-73-2Relevant academic research and scientific papers
One-pot, asymmetric and diastereoselective four-component synthesis of polyfunctional (Z)-alkenyl methyl sulfones with three stereogenic centers
Narkevitch, Vera,Vogel, Pierre,Schenk, Kurt
, p. 1674 - 1685 (2007/10/03)
The reaction of 1-(trimethylsilyloxy)cyclopentene (9) with (±)-1,3,5-triisopropyl-2-(1-(RS)-[[(1E)-2-methylpenta-1, 3-dienyl]oxy]ethyl)benzene ((±)-4a) in SO2/CH2Cl2 containing (CF3SO2)2NH, followed by treatment with Bu4NF and MeI gave a 3.0:1 mixture of (±)-(2RS)-2{(1RS,2Z,4SR)-2-methyl-4-(methylsulfonyl)-1-[(RS) -1-(2,4,6-triisopropylphenyl)ethoxy]pent-2-en-1-yl}cyclopentanone ((±)-10) and (±)-(2RS)-2{(1RS,2Z)-2-methyl-4-[(SR)-methylsulfonyl]-1-[(SR)-1 -(2,4,6-triisopropylphenyl)ethoxy]pent-2-en-1-yl}cyclopentanone ((±)-11). Similarly, enantiomerically pure dienyl ether (-)-(1S)-4a reacted with 1-(trimethylsilyloxy)cyclohexene (12) to give a 14.1:1 mixture of (-)-(2S)-2-{(1S,2Z,4R)-2-methyl-4-(methylsulfonyl)-1-[(S)-1-(2,4, 6-triisopropylphenyl)ethoxy]pent-2-enyl}cyclohexanone ((-)-13a) and its diastereoisomer 14a with (1S,2R,4R) or (1R,2S,4S) configuration. Structures of (±)-10, (±)-11, and (-)-13a were established by single-crystal X-ray crystallography. Poor diastereoselectivities were observed with the (E,E)-2-methylpenta-1,3-diene-1-ylethers (+)-4b and (-)-4c bearing (1S)-1-phenylethyl and (1S)-1-(pentafluorophenyl)ethyl groups instead of the Greene's auxiliary ((1S)-(2,4,6-triisopropylphenyl)ethyl group). The results demonstrate that high α/β-syn and asymmetric induction (due to the chiral auxiliary) can be obtained in the four-component syntheses of the β-alkoxy ketones. The method generates enantiomerically pure polyfunctional methyl sulfones bearing three chiral centers on C-atoms and one (Z)-alkene moiety.
Development of a new carbon - carbon bond forming reaction. New organic chemistry of sulfur dioxide. Asymmetric four-component synthesis of polyfunctional sulfones
Narkevitch,Megevand,Schenk,Vogel
, p. 5080 - 5093 (2007/10/03)
At low temperature 1-alkoxy-1,3-dienes add to sulfur dioxide activated by a Lewis or Bronstedt acid and generate zwitterionic intermediates that can be quenched by enoxysilanes. The resulting β,γ-unsaturated silyl sulfinates can be desilylated and reacted with methyl iodide to provide polyfunctional sulfones. Exploratory studies of this four-component synthesis of sulfones are reported. Enantiomerically pure derivatives containing up to three new stereogenic centers can be obtained using enantiomerically pure (E,E)-1 -alkoxy-2-methylpenta-1,3-dienes derived from α-methyl benzyl alcohols, including the Greene's chiral auxiliary. The stereochemistry of the reactions is consistent with a mechanism involving the suprafacial hetero-Diels - Alder addition of sulfur dioxide to the 1-alkoxy-1,3-dienes that are rapidly ionized into zwitterionic intermediates.
